For many years the typical hypodermic syringe has posed certain hazards to the community. Physicians, Nurses, and other healthcare professionals are keenly aware of the risks associated with use and disposal of these syringes. These risks include the possibility of physical injury by an inadvertent needle puncture and the more serious threat of cross-contamination and ensuing infection from an advertent "needle-stick" injury. Contracting a serious or deadly infection such as Acquired Immune Deficiency Syndrome (A.I.D.S.) or Hepatitis B from a contaminated hypodermic syringe is a very real possibility for healthcare workers. After penetration of an infected patient the cannula of the hypodermic syringe is contaminated by the blood of the patient. When the syringe is removed from the patient it becomes an immediate source of infection and poses a serious health threat to any individual who may come in contact with it.
Over the years as healthcare workers have become more aware of the dangers associated with the hypodermic syringe a number of strategies evolved to deal with the risks.
Needle covers which fit over the cannulas have been used to prevent needle-stick injuries. The hypodermic syringes are typically equipped with these covers or "caps" when they are shipped from the factory. At the clinical site the healthcare worker removes the cap, aspirates or otherwise inserts a medication into the syringe, and then injects the patient. The syringes may also be used to withdraw bodily fluids such as blood. The cannula is often re-capped by the clinician immediately after use to prevent a subsequent accidental needle puncture. This act in itself is hazardous to the clinician since most needle-stick injuries occur during recapping procedures.
The other most common method of dealing with the contaminated syringe is to dispose of the entire syringe in a thick walled plastic container which can be carefully disposed of later. After the syringe has been used it is placed into the SHARPS CONTAINER in its entirety without recapping the needle. The disadvantage of this method is that the sharps container must typically be a gallon or more in size in order to conveniently accommodate enough syringes to make disposal convenient. This method requires a healthcare facility to maintain and dispose of large numbers of bulky SHARPS CONTAINERS which contain used intact syringes. These syringes then become easy to steal by individuals who would use them for substance abuse.
Some hospitals allow one large SHARPS CONTAINER to be left in each hospital room, entirely unsupervised, until it is filled to the top with spent syringes. A child or irresponsible adult might remove some of the syringes out of curiosity. Thus, the risk of an inadvertent needle-stick injury actually increases as these intact syringes are stored in locations that are convenient to the clinical staff prior to disposal.
Another method of disposing of the syringes is to use a SHARPS CONTAINER that has a notched port into which the typical LUER-LOC needle tip can be fitted and unscrewed allowing the needle to fall into the container. The disadvantage to this method is that the process of unscrewing the needle tip almost always requires one hand to hold the container while the other hand rotates the body of the syringe. The clinician risks a needle-stick injury as he/she brings one hand onto the SHARPS CONTAINER while the other hand with the exposed syringe needle is brought down to the same location to insert into the collector. This action may be further complicated by the amount of space available for the activity, the location of the SHARPS CONTAINER, the size of the container, and many other possible factors.
Turning now to patented prior art, a number of inventors have tried to deal with the risks of needle-stick injury and cross-contamination.
U.S. Pat. No. 3,648,695 to Bowen (1972) discloses a pressurized applicator for formed medications which has an ejectable tip. The device cannot be used to aspirate fluids making it possible to load medicines from dispensing vials, to draw blood or bodily fluids, or to aspirate as a precautionary action to determine the anatomical location of the cannula tip relative to venous and arterial structures.
The barrel of the pressurized applicator and its corresponding applicator tip are designed for foam applications and will not provide an adequate seal for fluids having low viscosities. Additionally, the high cost of manufacture severely limits the use of this device for routine delivery of medication.
U.S. Pat. No. 4,026,287 to Haller (1977) shows a method by which the cannula bearing section of the syringe can be separated from the barrel and subsequently retracted within the barrel. The major drawback to this design is that the syringe must be disposed of in large bulk containers as described earlier. There remains the likelihood that after retraction the cannula may be re-exposed by subsequent forward pressure against the plunger rod. It is also possible for the cannula to dislodge from its attachment to the plunger enabling it to fall out of its barrel.
U.S. Pat. No. 3,320,954 to Cowley (1967) shows a method of separating the cannula from the syringe by means of a score located on an adaptor. The syringe is recapped after use and then the cap and syringe barrel are cocked simultaneously causing separation at a score line. U.S. Pat. No. 3,712,302 to Burke et al. (1973) shows a flexible needle guard which can be placed over a contaminated cannula to effect separation of the needle by continuous side to side motion. U.S. Pat. No. 4,027,669 to Johnston et al. (1977) shows a modified LUER-LOK syringe in which after injection the needle is recapped and the cap is cocked in a manner similar to that described by Cowley. All three of the above inventions have the disadvantage of requiring re-capping of the contaminated syringe in order to affect the separation and subsequent disposal of the cannula.
U.S. Pat. No. 4,233,975 to Yerman (1980) shows a design which renders a spent syringe unusable via an internal fluid blocking mechanism. U.S. Pat. Nos. 3,234,944 and Re. 28,713 to Stevens et al. (1962 and 1976) shows a method of supporting the needle on a hypodermic syringe. Neither of these patents relate to safe disposal of the contaminated cannula.
The present invention relates to safe, expeditious, and convenient disposal of the syringe cannula without requiring the operator to risk injury by recapping or otherwise placing bodily parts near the contaminated cannula. All of the existing prior art forms require recapping or dangerous manipulation of the syringe, or do not deal effectively with the safe cannula disposal issues related above.